The Molecular and Cellular Biology (MCB) training program at The University of Chicago is a long- standing interdisciplinary program that trains graduate students for independent academic and research careers in the biomedical sciences. This application requests support for years 38 through 42. Historically, the MCB program has actively supported 28-30 students for 2-3 years each, with a total of ~50-60 trainees in residence at any given time. Based on the success of our recent efforts to recruit highly qualified training grant-eligible students, 30 slots are requested for the next funding period. Students participating in this program are drawn primarily from four graduate programs: (1) Biochemistry and Molecular Biophysics, (2) Cell and Molecular Biology, (3) Development, Regeneration, and Stem Cell Biology, and (4) Microbiology. The mission of the MCB program is to train students to analyze biological processes using the conceptual and experimental tools of biochemistry and molecular, cellular, and structural biology. This training program is focused around a coherent set of scientific themes, but is intrinsically interdisciplinary in nature. The students take a cor set of courses in molecular biology, cell biology, and macromolecular structure. They subsequently pursue research projects involving a diverse set of model systems and approaches. The scientific interactions among the trainees are extensive, and are promoted by formal mechanisms that include monthly student presentations at the MCB Research in Progress series, meetings with trainee-invited distinguished lecturers, and the annual MCB Minisymposium, as well as the weekly MCB-affiliated Graduate Student Seminar series and the annual Molecular Biosciences retreat. The MCB Director or co-Director meets individually with all trainees in residence on an annual basis, to monitor their academic and research progress and to obtain feedback about the program. Historically, the MCB training program has taken the lead in developing a framework for comprehensive graduate training in the molecular biosciences, and this process is ongoing. For example, the MCB Director and co-Director are pioneering the development of an advanced bioethics course. In the Biological Sciences Division, the MCB training program provides a unique framework for fostering communication and collaboration between researchers who share an interest in approaching biological questions at the molecular and cellular level.